That was really interesting. I couldn't believe the fleece flower roots so I did some more searching and found these links about square water melons and sculpted gourds made by having them grow into a mold.

It seemed like the fleece flower roots were done in the same way that that the gourds and watermelons were - the roots were grown into a mold. Here is a link for a guy who does art by molding roots! I never found a definitive answer about the fleece flower because I got so sidetracked by these other interesting links people were putting out there.